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I've ran 22's for years and I've also used several tire brands: Pirelli, Nitto, Toyo and currently Hankook.
I am very attentive to my rides, maintainence and safety. Monitoring my tire pressure once or twice weekly! These extra low profile tires are impossible to visually tell they are too low or even flat!

So I had been having a slow leak in one of my rears that had no puncture. I initially contributed it to the varying temp changes lately. But decided to take it in to have the tire dipped to see where the leak was coming from. Upon dismount, there was a very obvious issue:
On the very inner side near sidewall, seperation and steel belt was visible.
Even though my tread is in great shape with thousands of miles left! No cupping no camber wear, nada!
The cause.... Weight Load exceeded.
They explained that they see this mostly on large diameter tires on luxury cars like mine. In fact, the air was leaking from there! Get this, the other side was worse!
So I drove back home and promptly installed my stock 19's which are like New. And THIS ladies and gents is exactly why I refuse to sell my stockers on any car I have. Unforseen shyt happens like this and no local shop has 22's on hand typically.
So after investigating weight ratings for these heavy ass cars, you generally want to be in the 100s. My Hankooks were 97. As are most 22s. So be careful and I suggest either jacking your car up or removing tires for a full visual even if the tread looks great! Ironically, fronts were fine. So lesson learned.
Now for frightening pics:
Note the nice tread and then on the inner side... Seperation that could've led to a BLOW-OUT!!!!

glad u didnt have a blowout with you or your family in the car........

Heres the deal tho: Inside wear on a BMW (tire) is very common because of the suspensions natural camber when the car is lowered. They are brutal on the insides of tires. Best defense is to keep the tire pressure up so that you arent ridin on sidewalls.

I need to check mine too, I been having the same problem with my rear passenger tire always seem to have a slow leak.

Definitely let us know and post up here buddy. I would NOT be surprised at all.

As far as the negative camber and lowering being the culprit... I say nope. Sure it CAN cause it, but you have seen in my pics just how much tread was left on the inside! Even the shop guys were like, "Man your tires were wearing very evenly considering your setup."
That's because as I've said for years... Run 40psi in these types of setups! I learned this from a custom shop owner back in the early 90's after he went thru much trial and error.
I strongly suggest if you have NOT already and it's been over 6 months since mounting your 22's... Unmount and Inspect.

There are a few things going on here that are causing it. Weight limit is one of them.

Basically a tire is meant to ride on it's treaded surface and sometimes a little bit on it's side, IE Camber (to an extent). Typically 1-1.8 degrees of camber is perfectly fine. However go past this and tires can fail pretty badly since the sidewalls aren't designed for that specific duty.

EDIT: Also stretching a tire on a rim it's not designed for can also put a LOT of pressure on the sidewall and the cords that hold the tire together, which it looks like in the first picture!

You said you keep your tires around 40 PSI, this over inflates the center of the tire putting a slight bulge in it. The steel cords have to work harder to make sure the tire stays within it's shape. As well with 40 PSI the pressure can vary a bit, I wouldn't be surprised that the tires get up to 45 PSI when warmed up! This large change in pressure plus the high pressure is putting a large strain on the cord, and as well the rubber surrounding it.

Heavy weight is a huge killer of tires. Remember they are rated to only handle a certain load per tire, and that's under optimal conditions! In this case the OP had a tire with cords that were straining already, and then may have exceeded the weight limit putting even more of a strain on the cords and the surrounding rubber.

Add some driving into the mix and then what you have is the rubber separating from the stressed cord, and then appearing like what the OP posted. Over time this can get worse with the tread/sidewall separating or a blowout!

Definitely let us know and post up here buddy. I would NOT be surprised at all.

As far as the negative camber and lowering being the culprit... I say nope. Sure it CAN cause it, but you have seen in my pics just how much tread was left on the inside! Even the shop guys were like, "Man your tires were wearing very evenly considering your setup."
That's because as I've said for years... Run 40psi in these types of setups! I learned this from a custom shop owner back in the early 90's after he went thru much trial and error.
I strongly suggest if you have NOT already and it's been over 6 months since mounting your 22's... Unmount and Inspect.

~ Big Marcus

u can say "nope" but its the truth....sorry TXStyle but its not that it CAN...It WILL

If your tire is bad on the inside its simply because you ran it under the needed psi and the associated CAMBER put too much pressure on the inside tire wall. (B) You're runnin too much camber (c) needs an alignment (d) we can rule out defective tire because your other side is worse.

someone saying a tire "looks good" doesnt knowtiresoutside of the tread they see. Its impossible to look at a tire and determine if it has sidewall or internal wire damage...usually caused by running it without the proper tire pressure.

over inflation will wear out the center of the tire.

also, its not good to throw out random PSI numbers...what works for you in your area/conditions may not work for someone that lives across the country in different climates/conditions. Not all manufacturers use the same ratings and recommendations, etc,etc... even model numbers within the same manufacturer will have different characteristics and rating.

blah, blah , blah...etc.

Anywayz, I try to look at the inside of all my ( FALKEN ) tires at least once a year. The cars on air get checked more often because they camber in due to being lowered....My Drift cars just get their tires tossed out.

+1 to camber. I just had the exact same outcome on my rear tires, and they are appropriate weight rated 20's. outer edge of tires had most of the tread left, the inner edge/shoulder was showing the cords.

Bingo! Lol! Not gonna argue or debate on shyt I've been doing for 20yrs (rolling bigger wheels on various cars).
This shyt that happened to my tires is NOT camber or suspension related.
Weight Load Exceeded
In fact, lets keep this thread limited to examples of "weight load" related tire failure to reduce confusion.
Thanks!

Bingo! Lol! Not gonna argue or debate on shyt I've been doing for 20yrs (rolling bigger wheels on various cars).
This shyt that happened to my tires is NOT camber or suspension related.
Weight Load Exceeded
In fact, lets keep this thread limited to examples of "weight load" related tire failure to reduce confusion.
Thanks!